ACI 318 and ACI PRC-211.1-22 Do Different Jobs
ACI 318 is a structural concrete building code; ACI PRC-211.1-22 is a guide for selecting and adjusting concrete proportions. A useful calculator has to respect that boundary instead of treating one document as a substitute for the other.
Which ACI 318 edition governs?
ACI publishes new code editions periodically, but publication does not automatically change every project. The governing edition is the one adopted by the applicable jurisdiction and/or incorporated into the project documents for the relevant design and permit context. In 2026, ACI CODE-318-25 is published, while many live jurisdictions and projects can still reference earlier adopted editions.
What ACI PRC-211.1-22 contributes
The 2022 guide provides a structured preliminary proportioning workflow: starting water and air relationships, an approximate strength-versus-w/cm relationship, coarse-aggregate bulk-volume guidance, absolute-volume closure and adjustment through trial batches. Those relationships help build a first mixture; they do not certify durability or project compliance.
Why this site does not hard-code one ACI 318 durability table
Specific durability values can change between code editions and depend on exposure assignments. A website cannot know which code edition a particular city, owner or project has adopted. The calculator therefore records exposure as context and asks the user to enter a verified maximum w/cm or other project minimum when one applies.
How to check a real project
- Identify the jurisdiction and project specification.
- Confirm the adopted ACI 318/code edition.
- Assign exposure categories through the responsible design/specification process.
- Extract the actual maximum w/cm, strength, air and material restrictions.
- Enter verified limits into the preliminary proportioning tool.
- Confirm the resulting mixture through the required trial, submittal and production process.
Do not confuse “current publication” with “current project requirement”
Both facts matter. Current publications are important for technical awareness, but a project can legally and contractually remain tied to a different adopted edition. This site therefore dates technical reviews and avoids silently replacing project requirements with the newest publication number.